A father was arrested on charges of faking cystic fibrosis in his son by keeping the boy thin and fabricating medical bills - a story that authorities say fooled even his estranged wife. Michael Bradway, 38, who has a history of forgery and larceny, was arrested on Wednesday. The boy, now nine, was put in state care last year and immediately began to gain weight and thrive, according to court papers. He now lives with his mother.

Cystic fibrosis, which can be fatal, causes thick, sticky mucus to build up in the lungs and digestive system. It affects about 30,000 people in the US.

The authorities said Mr Bradway began fabricating medical bills in 2001 when his son was five. He allegedly put him on a severe diet to make him thin and, to avoid doctors, told school officials that the boy could not be immunised for religious reasons. He also allegedly convinced school officials that his son needed to take medication every two hours. Mr Bradway told his in-laws his son would probably need a lung transplant, and that a hospital in Canada specialised in such cases, the arrest affidavit said. They eventually contributed $38,000 for medical care.

The boy's estranged mother, Ericka Hollander, began to question the diagnosis more than a year ago and asked for medical records, the authorities said. Her lawyer, Michael Sconyers, called the situation "despicable". "This child is growing up for four or five years thinking he had a fatal disease and he was getting worse," he said. "She was devastated."

Mr Bradway was convicted in 1994 of larceny and forgery for operating as an unregistered broker in Massachusetts and embezzling $167,000, authorities said. He was sentenced to one year in prison.